The present project is concerned primarily with the nature and role in problem solving of control mechanisms which determine how people use their available knowledge. Our goals for the first year have been to demonstrate, refine, and extend the "first approximation" mechanism proposed and tested in Scandura (1974). Whereas that study was concerned primarily with the derivation of new solution procedures, we have concentrated during this year on demonstration studies, involving simple problem solving, that deal with the role of control mechanisms in retrieval, subgoal formation, and rule selection. In each case, demonstration studies were conducted with 7-9 year old children under idealized training and test conditions to determine the viability of the generalized mechanism. With only a very small number of exceptions, the data were directly consistent with the postulated mechanisms. In this regard it is important to emphasize that these results held in deterministic fashion. That is, individual subjects succeeded on specific problems where and only where the postulated mechanism indicated that they should. During year two, the immediate goal will be to determine whether the control mechanism, identified and known to be uniformly available to children from about the age of seven, is also available to younger children (from about the age of four). BIBLIOGRAPHIC REFERENCES: Scandura, J. M. Structural approach to instructional problems. American Psychologist, 1977, 32, 33-53. Scandura, J. M. IPN symposium discussion. In H. Spada and W. F. Kempf (Eds.), Formalized theories of thinking and learning and their implications for science instruction. Bern: Huber, 1977, in press.